ATROPISOMERIC DIARYL-CORE PHOSPHOLE LIGANDS - PD-II AND PT-II COMPLEXES WITH P-PHENYL DINAPHTHOPHOSPHOLE

The behaviour of P-phenyl dinaphthophosphole (L), the first phosphole with axial chirality, towards some ds metal centres has been investigated. L acts as a monodentate phosphorus ligand and readily substitutes neutral or anionic ligands coordinated to Pd(II) and Pt(II) centres. New complexes L MCl2 with exclusive (M = Pt) or predominant (M = Pd) cis geometry have been obtained by reaction with K2[PtCl4] and (PhC2)2PdCl2. Reaction of L with ortho-metallated chloride bridged dinuclear [(C-N)MCI]2 complexes (HC-N - 2-benzylpyridine, M = Pt; HC-N = N,N-dimethyl-(R)-alpha-methylbenzylainine, M = Pd) promotes bridge splitting leading to the mononuclear species L(C-N)MCI with a trans P-M-N arrangement. The X-ray structure of the Pd complex shows that the coordination around the metal is essentially square planar with normal bond distances. The dihedral angle between the average planes of the naphthyl groups of the phosphole (33-degrees) and Tolman's cone angle theta of the ligand (136) have been determined. In some complexes, the phosphole ligand is fluxional at room temperature and undergoes rapid atropisomerization of the binaphthyl framework even in the bound state.